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Review 2 of 3
Price Paid:
$500.00
from online - vacuum tube valley Summary:
I've been trying to get my phono stage entirely tubified, and this was the last link. HW is: Decware Zen 84B amp, Decware ZTPreamp, Oracle Alexandria TT with stock arm, Sumiko BP, homebuilt speakers from North Creek Music systems, Decware cable from phono to phono stage to preamp and Vampire Wire in the rest, incl speaker cables. The unit I have is a PP-2, which is close enough to the PP-1. Main difference is the PP-2 can handle both MC and MM, and the PP-2 uses 4 12AX7 vs the 3 in the PP-1. I liked the simple, clean design of the AS-USA preamp. The power supply is on one PCB, and the audio signal is on another. There is ZERO 60Hz hum in this - I tested it by putting the needle on a record while the record was NOT spinnning, and cranking up ALL volume controls. Just got hiss from the components. I replaced ALL resistors on the audio board with Holco metal films, and a couple of tantalums. Also replaced ALL caps on the audio board with Orange Drop 716Ps and a couple of Paper in Oil on the inputs and outputs. Also replaced ALL caps on the power supply board with Panasonic caps. All wiring was done with teflon coated wire from Welborne and Angela. Also wired up separate ground wires for EACH ground point. This is a minor nit, but I figured on a phono section, because of the low voltages, you need to remove ANY potential source of noise. I just went to Home Depot and got a large grounding part from their electrical section, and used that for the star ground point inside the preamp. I then crammed each separate ground wire into it - it was a tight fit - didn't think they would all fit - there were about 9-10 separate wires to go into it. I got some nice silver wire on sale at Angela for a couple of bucks which I used for ALL ground points. Anyway, there is NO hum noise at all on this unit, so I am sure this grounding helped. Because of all the premium caps I used, I had to build a small extension as all the new caps stick out the bottom. I had some spare maple sitting around from another project and added about 1" to the bottom of the unit. It looks a little weird, but it works, and there are no wires poking out. My wife actually thought it did not have any function in the stereo unit. I need to add some velcro so the top and bottom pieces stick together, but it is working fine. I was also going to add a piece of lead in between the audio board and power supply board to further shield the audio board from any stray EMI fields. The sound with the stock CHinese 12AX7 is OK. I got some JAN5751 and some GE (I think) 12AX7 from Uncle Ned, and I much prefer the 5751 - fuller bottom end, excellent mid-range and clean, clear highs. They also supplied tube shields, but I could not get them to fit on top of the tube sockets they supplied. Other than the minor nits, it worked fine the first time I fired it up, and has been playing great for the past 8 months. My longest session has been 8 straight hours, with NO listener fatigue. I only quit because my wife was getting home from work, and i would get the usual "Turn that thing down!" But I'm sure none of you reading this ever get THAT. :-) Hope this helps anyone reading this. Strengths:
relatively low price, simple, clean design internally, adjustable output, handles MC and MM cartridges Weaknesses:
low quality parts internally Similar Products Used:
PS Audio IV preamp - solid state unit
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